nsIPropertyBag
:batterymanager buildid:"20140529161749" cookieenabled:true donottrack:"yes" geolocation:geolocation language:"en-us" mimetypes:mimetypearray mozalarms:null mozapps:xpcwrappednative_nohelper mozcameras:cameramanager mozconnection:mozconnection mozcontacts:contactmanager mozid:null mozkeyboard:xpcwrappednative_nohelper mozpay:null mozpermissionsettings:null mozphonenumberservice:phonenumberservice mozpower:mozpowermanager moztcpsocket:null online:true oscpu:"windows nt 5.1" platform:"win32" plugins:pluginarray product:"gecko" productsub:"20100101" useragent:"mozilla/5.0 (windows nt 5.1; rv:30.0) gecko/20100101 firefox/30.0" vendor:"" vendorsub:"" __proto__:navigatorprototype from here we can easily see the operating system version.

Proximity Events - Web APIs
example window.addeventlistener('userproximity', function(event) { if (event.near) { // let's power off the screen navigator.mozpower.screenenabled = false; } else { // otherwise, let's power on the screen navigator.mozpower.screenenabled = true; } }); specifications specification status comment proximity sensorthe definition of 'proximity events' in that specification.